While editing this question to include a better title, I noticed that the body of the text had a stray lowercase i, and went to change it.

The error came back that my edit was too short (less than 6 characters). I was momentarily confused, because the title was all-new and plenty long, and then figured out it meant in the body. Could/should we either count title changes toward the minimum character change count or just mention that the error refers to the body of the question?

Yeah, this seems utterly wrong: your edit to the title was plenty significant enough all on its own; at that point, minor body edits could be a cherry on top.

Given the importance of having a good title, I don't see any good reason why a major title edit shouldn't allow minor body edits to ride along as well. Especially considering you can submit the title edits alone and then someone else could submit slightly more involved body edits, thus requiring two separate approvals anyway...

Just ran into this problem again on Programmers (ran into it many times on StackOverflow when I was <2k).

It's fairly common to have a well-written (or decently-written) question with a misleading/inaccurate title, or a title that is filled with all of the question's tags. Sometimes the user doesn't know how to articulate their problem in title form. Fixing just the title is sufficient, but if there are minor typos in the body, they need to be left there.